1. Field
Example embodiments relate to a vertical light emitting device.
2. Description of the Related Art
As semiconductor light emitting devices (LED), especially, Gallium Nitride (GaN)-based light emitting devices, have received considerable attention as being highly efficient, environment-friendly light sources. They are being used in a wider range of applications such as back light units for various types of displays, LCDs for mobile phones, LCD TVs, and monitors, light sources for automobiles, and light sources for general illumination. With a broader use of GaN-based LEDs, high output, large area LEDs are gaining popularity, and vertical structure LEDs have emerged as a suitable structure for high power and large area LEDs.
Since large-area vertical GaN-based LEDs with high output power have a large chip area and are driven by high current, current spreading is very important in LED design in order to spread current evenly across the entire chip area in an LED. Non-uniform current spreading may cause current crowding, i.e., current concentration in local regions of an LED chip. The current crowding effect may increase current density at the local regions of LED chip, thereby degrading the efficiency of the LED while increasing a driving voltage. The current crowding is also responsible for local overheating and a short LED lifetime, thereby degrading device reliability. Driving current as well as chip area has been increasing as the industry pushes for higher output power LEDs. Accordingly, there is an increasing need for development of current spreading design and technology that can mitigate current crowding problems.